NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
Bit
R
7
6
5
4
3
2
1
0
FRC_TIMER[7:0]
W
Reset
0
0
0
0
0
0
0
0
= Reserved
7.11.7.1 Software handler requirements
Application developers should adhere to the following steps when entering and exiting
software handler for the FRC:
1. Disable all interrupt sources
2. Write PMCT[0] = 1
3. Control PMCT and/or read FRC_TIMER as needed
4. Write PMCT[0] = 0
5. Enable all interrupt sources.
7.11.7.2 Initialization recommendations
Due to being clocked by the LFO which operates contentiously while power is applied,
application developers that desire the FRC to start from 0x0000 may initialize the FRC by
the following process:
1. Disable all interrupt sources
2. Write PMCT[0] = 1
3. Write PMCT[5] = 0 and PMCT[7] = 1
4. Write PMCT[5] = 1
5. Write PMCT[0] = 0
6. Re-enable appropriate interrupt sources.
These steps can be ignored if the application does not require the FRC to start from
0x0000.
7.12 System STOP exit status register (SIMSES)
The SIMSES register at $180D can be used to determine the source of an MCU
wakeup from the STOP modes. The flags are as shown in Table 52. All of the flags are
automatically cleared when the MCU goes into a STOP mode. Writes to any of these bits
are ignored.
Table 52.ꢀSIM STOP exit status (SIMSES) (address $180D)
Bit
R
7
6
5
4
3
2
1
0
KBF
IRQF
TRF
PWUF
LFF
RFF
W
Reset
0
0
0
0
0
0
0
0
= Reserved
FXTH87ERM
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© NXP B.V. 2019. All rights reserved.
Reference manual
Rev. 5.0 — 4 February 2019
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